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Title: MATING DISRUPTION EXPERIMENTS: DOSE-RESPONSE AND SKIPPED-SWATH TESTS

Author
item SHAROV - VA TECH
item Thorpe, Kevin
item TCHESLAVSKAIA - VA TECH

Submitted to: Annual Gypsy Moth Review Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/15/2002
Publication Date: 10/2/2002
Citation: Sharov, Thorpe, K.W., Tcheslavskaia 2002. Mating disruption experiments: dose-response and skipped-swath tests. Annual Gypsy Moth Review Proceedings.

Interpretive Summary: The gypsy moth, a serious pest of oak trees in the northeastern United States, continues to expand its range to the south and west. Due to concern over the potential adverse ecological impacts of insecticide spraying, there is increasing interest in the use of mating disruption to slow the spread of this pest. Mating disruption is an environment-friendly ymethod of eradicating small isolated infestations by applying a large enough dose of the gypsy moth sex pheromone, disparlure, to confuse males and prevent mating. This paper reports the results of two tests conducted in 2001 to determine 1) the relationship between application rate and treatment effectiveness and 2) if it is possible to leave gaps between treated areas and still prevent mating. The results of the first study showed that mating was disrupted at application rates from 15 to 75 g/ha, but not at lower application rates. The second test showed that, when 90 m mgaps are left between treated areas, mating is disrupted but not as much a with more uniform spray coverage. Additional tests will be conducted to determine if narrower gaps could provide more effective mating suppression. This information will help government agencies and gypsy moth control specialists who are involved in gypsy moth mating disruption programs determine more cost-effective ways to use this pest management approach.

Technical Abstract: Tests were conducted in central Virginia during 2001 to determine the dose response of low-density gypsy moth populations to aerially-applied mating disruptants and the effectiveness of mating disruptant applied in strips separated by 90 m gaps. For the dose response test, 25-ha plots were treated with an experimental microcapsule formulation at application rates ranging from zero to 75 g active ingredient per ha. Treatment effectiveness was evaluated by reduction in male moth capture in pheromone-baited traps and reduction in mating success of virgin females tethered to tree trunks. Application rates less than 15 g/ha was not effective. Maximum effectiveness occurred at 75 g/ha, which was the highest dose tested. For the skipped swath test, a plastic laminate flake formulation was applied in five 30 m swaths each separated by 90 m. Each swath was treated at a rate of 150 g/ha, so that the average application rate over the whole plot was 37.5 g/ha. Lines of pheromone traps and tethered females spaced at 30 m intervals through the plots were used to evaluate mating suppression. Overall, mating success was reduced from 81% in an untreated area to 5% in a treated plot. However, trap capture was slightly higher between treated swaths than in the centers of the treated swaths, indicating that the gaps between the swaths may need to be <90 m to effectively suppress mating.